package UdpEchoServer2;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpEchoServer {
    private DatagramSocket socket = null;

    public UdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);//手动指定服务器端口
    }

    public void start() throws IOException {
        System.out.println("服务器启动");
        while (true) {
            //1. 收到请求
            DatagramPacket requestPacket = new DatagramPacket(new byte[1024],1024);
            socket.receive(requestPacket);
            //2. 解析请求
            String request = new String(requestPacket.getData(),0, requestPacket.getLength());
            String response = process(request);
            //3. 发送请求
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),
                    response.getBytes().length,requestPacket.getSocketAddress());
            socket.send(responsePacket);
            //4. 打印日志
            System.out.printf("[%s:%d],req: %s,resp: %s\n",requestPacket.getAddress(),requestPacket.getPort(),
                    request,response);
        }
    }

    private String process(String request) {
        return request;
    }

    //启动服务器
    public static void main(String[] args) throws IOException {
        UdpEchoServer udpEchoServer = new UdpEchoServer(2025);
        udpEchoServer.start();
    }
}
